From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Rajnoha Date: Mon, 02 Aug 2010 21:24:57 +0200 Subject: [PATCH] Add check for semaphore kernel support Message-ID: <4C571B89.2030309@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit We also need to check for kernel semaphore support (part of System V IPC, kernel's CONFIG_SYSVIPC). If not compiled in the kernel, we need to disable udev synchronisation code and show a warning message at least (so one knows that it should be added in the kernel or that libdebmapper should be compiled without udev_sync alternatively). Inspired by util-linux-ng's ipcs code. Initiated by the problem reported here: http://bugs.gentoo.org/show_bug.cgi?id=330375 Peter --- libdm/libdm-common.c | 33 +++++++++++++++++++++++++++++---- 1 files changed, 29 insertions(+), 4 deletions(-) diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c index 438e461..23dd761 100644 --- a/libdm/libdm-common.c +++ b/libdm/libdm-common.c @@ -60,6 +60,7 @@ static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR; static int _verbose = 0; #ifdef UDEV_SYNC_SUPPORT +static int _semaphore_supported = -1; static int _udev_running = -1; static int _sync_with_udev = 1; static int _udev_checking = 1; @@ -929,6 +930,23 @@ int dm_udev_wait(uint32_t cookie) #else /* UDEV_SYNC_SUPPORT */ +static int _check_semaphore_is_supported() +{ + int maxid; + union semun arg; + struct seminfo seminfo; + + arg.array = (unsigned short int *) (void *) &seminfo; + maxid = semctl(0, 0, SEM_INFO, arg); + + if (maxid < 0) { + log_warn("Kernel not configured for semaphores (System V IPC). " + "Not using udev synchronisation code."); + return 0; + } + + return 1; +} static int _check_udev_is_running(void) { @@ -958,20 +976,27 @@ bad: return 0; } -void dm_udev_set_sync_support(int sync_with_udev) +static void _check_udev_sync_requirements_once() { + if (_semaphore_supported < 0) + _semaphore_supported = _check_semaphore_is_supported(); + if (_udev_running < 0) _udev_running = _check_udev_is_running(); +} +void dm_udev_set_sync_support(int sync_with_udev) +{ + _check_udev_sync_requirements_once(); _sync_with_udev = sync_with_udev; } int dm_udev_get_sync_support(void) { - if (_udev_running < 0) - _udev_running = _check_udev_is_running(); + _check_udev_sync_requirements_once(); - return dm_cookie_supported() && _udev_running && _sync_with_udev; + return _semaphore_supported && dm_cookie_supported() && + _udev_running && _sync_with_udev; } void dm_udev_set_checking(int checking)